The present invention relates to a method for delivering a coffee beverage by centrifugation.
A traditional extraction method for preparing short coffee beverages such as ristretto or espresso consists in applying a water piston at high pressure from one side of an enclosure containing ground coffee powder and extracting a coffee extract at the opposite side of the enclosure. This method promotes the delivery of coffee beverages experiencing high aroma and flavour intensity which are particularly appreciated by coffee gourmets.
Other methods consist in brewing a long coffee under low pressure or gravity such as by the use of a drip coffee maker. The low pressure involved during extraction provides coffee with a lower aroma intensity. Therefore, unless a large excess of coffee powder is placed in the coffee maker, often the coffee is watery, has a low aroma/flavour profile and has usually no sufficient foam.
Due to the low pressure, the drip coffee method is not adapted for delivering short coffee beverages as it does not provide enough body, flavour, aroma intensity and crema.
The preparation of coffee by using the centrifugation is also already known. The principle mainly consists in providing ground coffee in a receptacle, feeding liquid in the receptacle and rotating the receptacle at elevated speed to ensure interaction of liquid with powder while creating a gradient of pressure of liquid in the receptacle; such pressure increasing gradually from the centre towards the periphery of the receptacle. As liquid traverses the coffee bed, extraction of the coffee compounds takes place and a liquid extract is obtained that flows out at the periphery of the receptacle.
Another problem encountered with the known coffee centrifugation processes relates to the non-homogeneous interaction between liquid and coffee that negatively affects the quality of coffee extraction. In particular, it may be that liquid does not wet uniformly coffee or water may find preferred flow path in the coffee powder or water pockets form in the coffee receptacle, etc. As a consequence, the transfer of coffee solids into liquid is not optimal. Also, coffee flavour and aroma intensity can be lost. This problem is particularly sensible when a short coffee beverage such as ristretto or espresso-type coffee is produced by centrifugation because the loss on coffee quality (strength, aroma/flavour, crema, etc.) is usually more perceivable than for longer coffee (lungo or longer coffee).
WO2008/148834 relates to a capsule for use in a beverage preparation device using centrifugation forces to extract the beverage extract wherein, as an example, the capsule may contain 6.5 of coffee powder of particle size of 260 microns. The capsule is rotated at about 8000 rpm at a liquid flow rate of about 2 gram/second.
There is a need for delivering a short coffee having an improved quality, in particular, its aroma and flavour intensity so that it matches the quality of the coffee obtained by the traditional extraction method. The present invention provides a solution to this need.
There is also need for delivering a selection of coffee beverages by a common method while achieving improved coffee quality results. In particular, there is a need for improving the extraction quality of coffee beverages of different volumes such as short, medium and/or long coffees while reducing the disadvantages of the known methods.
There is also a need for improving the “crema” on the top of the coffee beverage. These needs are now met by the present invention.